A print sheet may include one or more images printed on a standard size paper sheet. When used to form a case for a hard cover book, the print sheet must be trimmed to fit the specific dimensions of the book. After it is trimmed, the print sheet may be glued or otherwise secured to a rigid front panel, rigid back panel and rigid spine to form a book case which forms the front cover, the spine, and the back cover of a book. A book block (i.e. the stack of bound pages in the book) may be secured to the book case to complete the fabrication of the book.
In mass production of hard cover books, there is a large volume of print sheets featuring identical images, and all of the print sheets are trimmed to the same size. A large volume of print sheets may be trimmed with an industrial guillotine configured to cut through a stack of sheets at some specific distance from the edge of the stack for the specific dimensions of the hard cover book. In some cases fiducials or corner cut marks are used to visually indicate the expected cut position to the guillotine operator.
When the size and/or location of the images printed on the print sheets within a stack vary, the industrial guillotine may be impractical, requiring reconfiguration for each variation in size and/or location of the image on the print sheet. Therefore, in smaller scale production, the print sheet may be cut by hand. However, cutting by hand is time consuming and may be inaccurate.
Some steps in the case-making process require registering the trimmed sheet and this registration is typically done by moving the sheet so one edge (perhaps the top edge) contacts a stop bar and then the sheet is slid along this stop bar until an adjacent sheet side edge contacts a side stop. This process provides complete sheet registration. However, if the print sheet is not accurately trimmed, the printed graphics on the sheet may not be properly positioned. Case-making is the process of adhering a cover sheet to one or more rigid panels and folding the cover sheet around the panel edges for a neat appearance. Typically the amount of material folded over is approximately ¾″. When the cover material is printed, proper registration of the printing to the panel may be more important than the amount of material folded over. Direct registration of the cover sheet printing to the rigid panels is most desirable in the case-making process. When this is not practical, accurate trimming of the print sheet is important.